What you're probably looking for is a way to load data into your template from variables. But you're going about this the wrong way. Use a hash to store the data, and regex to substitute:
use strict;
use warnings;
my %vars = (
var1 => 'MyValue',
);
my $here_is = <<SOME_TEXT;
I want to print something
with a value %var1%
and some other text load
etc etc
SOME_TEXT
$here_is =~ s/%(\w+?)%/$vars{$1}/g;
print $here_is;
You may also want to look at loading the template from a file or __DATA__, so you're not forced to allow the extra line break that
<<TAG makes mandatory.